RS Media Fried electronics

I recently received a RSM from the UK which I purchased as spare parts knowing it had some issues. The foot pads aren't used and plastic still on the arm tubes with the body in pristine conditions so it was used maybe once or twice before this electronic yellow ceramic dohicky blew on the media board. I can tell it is the NON USBNET model and I've spent a couple hours searching online but have yet to find any details on it. It is (was) marked A 107A u12k5, anyone have a clue to what it is or where I could get one?

Thanks Rudolph, yes it is two leads, unfortunately I could not follow either of those links. You say it should be a 10uF capacitor, Would you be so kind as to give me part number? I think the site you tried to link me to is mouser.com correct?

Mouser part number 80-B45196H2106K109 (Kemet, 10Uf tantalum smd 10V) is the one I tried to link to. I found it by searching mouser for "10uF capacitor" and comparing their product photos to yours is all. Another similar looking one is 80-T494B106K016, which is 16V.

There are also some that look close to the one in your photo that say they're ceramic (MLCC). The band on one side of yours leads me to think it's a polarized one though, and ceramic usually aren't (in my limited experience) so I _think_ you'd be better off with the tantalum one. I'm also not sure about the voltage rating. I don't know what voltage the Media puts to that cap, so 10V may be too low (who knows, maybe WowWee put a 10V cap in a 9V circuit and that's why it failed?)

You'll definitely need to compare package sizes too. I have no idea how big the cap in your photo is, but I do know that if you order up an '0204' sized SMD cap you might need a microscope to find it in the packaging.

Thanks Rudolph, I'll go ahead and order a couple of 80-T494B106K016 16v tantalum ones. Cross my fingers that's the only thing that blew. I took a real long hard look and the rest seems ok. I powered the RSM up without the media board and I see his eyes and LCD light up then he shuts off, so to me that is a good sign. Right? haha

Here's proof I don't really know what I'm talking about. A re-check of numbering says that "107" would actually be 100uF, not ten. (10 with 7 zeros behind it is 100,000,000pF). If you haven't ordered already bump it up a zero. Sorry.

Hey Freddy,
I can help you here a bit I think. I can confirm that it is a tantalum capacitor and 107 is indeed 100uF. (BTW the white writing on the board says its numbered 'C35' - the C indicates Capacitor)
The capacitor will also have a voltage rating - but we cant tell this from looking at it.
But judging by the circuit around it I think this capacitor is likely part of the voltage regulation circuit (I guess that the 3 pin chip beside it is a voltage regulator and the brown part above that is an inductor/transformer (to step down the voltage?)
It seems that the capacitor is bridging between the ground and supply voltages (judging by the large tracks it is connected to).
So this is good news - it means that if you get a capacitor with a voltage higher than the supply voltage it is likely to work OK. So I'd try 16V or 25V will probably work OK. 10V is probably OK too.

Also note that a tantulum capacitor is polorised - when you put the new capacitor on you should put the black bar (printed on top) at the same end as the original one.

Also I suggest that you order a few capacitors.....its possible that when you replace it, it may blow again!! This could happen if the fault is happening in another part of the board and it is just causing the capacitor to blow.
A safer way to test this would be to power him up , but only for 10 seconds then power him down, then feel the components on the board and see if any are getting hot.
If everything is feeling cool then power him up again and leave him on for 20 seconds. Then 30 seconds. Keep going like this , if nothing is getting too hot then let him power fully up.

Good luck.....
Have you heard of this saying - I love it - " All electronic devices work by using the smnoke inside them , if you let the smoke out then they will always stop working"

Thanks Helibot for the reasurance and the tips, definitly will get a few of them just in case the smoke gets out again. I'll get 16v ones and replace in correct polarized position. Also the tip on powering up and testing the temps is a great idea, might just spring for one of those laser temp pens. I'm thinking that perhaps this RSM was powered up using the wrong adapter 12v or more since they are sold w/o adapters in the UK.

Hi Freddy,
Using a wrong power adapter could have been the cause.
Another idea is to use a Bench powersupply instead of batteries or poweradapter.
With a bench powersupply you can set the voltage and importantly the max current. So if you cct draws too much current then the power supply will start dropping the voltage (or cut out ) before any damage is done. So a bench powersupply set to ~7V and max current of 500-750mA should let him powerup OK (if nothing is drawing too much current). BUT once he starts moving you need a much higher max current. He can draw really large currents (over 2.5 amps) while the motors are moving!!

I heared more extended variant, which tells that electronics is like magic: it is made with magical smoke and mirrors. If you open any electronic chip, you will see a tiny mirror inside ;). But then if you power it on - magical smoke will escape from that mirror and chip will not work!

Helibot, I think you have mentioned you have a couple of these blown components in your RSM aswell (the neck motor I rememeber)Would you take a look a this website www.sparkfun.com to see if you could identify these since im not quite sure what im lookiing for. I'll order these parts and send some your way for the help. I still havent ordered the 100uf 16v capacitors and I have no clue what the CB38P 29517 in te picture above the last is. All I know is that there is no blue smoke or tiny mirrors left inside it, I looked.

I have been searching around the net, and I found the components in the top picture!They are 3-Pin 300mA Low Dropout Linear Regulators.I found a PDF on the component and it says all about them and the model number. Interesting thing is, it says it needs 2 Electrolytic Capacitors on CIN and COUT. And in your picture, the board has just that beside the chips! :D

Hello Jamie and Freddy,
Thanks for the heads up Jamie. I was expecting the CB38P or 29517 to be part of the part number....but thats not the case - the part number is SS6734G (but I guess thats too long to print on the small package) so they print the code "CB38P".
So the marking CB38P for a SS6734G means it is a 3.8v version in a SOT-89 package. The photo shows that it is a SOT 89 package. So its looking likely.
I also found that marking CB38 is also used on a AIC1734-38CXT which seems to a duplicate component of the SS6734G.
But I have searched a few sources and havenÃ‚Â’t found anywhere that sells either of these :-(

So I think we need to find a suitable replacement from another manufacturer.
So I looked for a Low dropout voltage regulator with 3.8v output that can supply 300mA of current - and guess what I couldnt find any :-(. But I have only searched a few places so we may still find some.... but thats all I have time for tonight. I hope to spend some more time haveing a look on the weekend.

Freddy (or anyone?) Do you have a working bot that is apart? (mine are back together again!) If so can you get to the "CP38P" part while it is running? If so can you test the voltage at the botom right hand pin of the "CB38P" part? I think it should be 3.8V (just want to be sure before I invest a lot of time finding a replacement part.)

Hey guys, sorry I havent done this. I'll make sure to remember to test this. So I've been putting off ordering the other parts just in case I can order all the parts at once from mouser and save on shipping.
Freddy

Hi there I have a RS Media Robot which is about 3 years old. About 1 year a go He stopped working(I mean he no long powers up.) I have tried new battery's and plugging the mains adapter but nothing happens when I switch it on.

As I am not a electronics whiz does anyone know if there is anywhere in the UK I can send the robot to get it fixed or is there any easy checks that can be done. I have checked out the photos above but I have no idea where I would start to check to see if anything is out of place or broken does anyone out there have some kind of wiring diagram that shows what all the wires are for.

We have taken off the media board and have inspected it under a digital microscope. I found that AC91 on the media board was lifted on the one side. I have soldered this back on and reassembled the robots. I plugged the robot into main adapter and switched the robot power button on, but he still will not power up at all, no LCD no eyes no speech. Nothing!

We have taken the Motor board and the Main Robot board off and checked them under a x100 magnifier. There is no sign of burnt components, or lifted component on any of the board we have checked so far.

We have power going up to the main robot board. Do do this we checked that there is a 7.5v current on the wire that connect for the power on off button of the robot to the main robot board with the aid of a digital multimeter.

For the past week Jamie has been great, helping us guiding us through the disassembly of the robot. He has offered to try and repair the fault if I send the boards to him. This is great although he lives in Australia and I live in the UK so the shipping costs are not cheap. I would like to try as many thing as possible to fix the robot myself first with the help of the robo-community before sending it away.

I am lucky as I work in an electronics factory and should be able to get hold of capacitors, resistors, and other components if any are needed to repair the robot.

I do have another working RS media which is my sons. Could I disassemble this robot and try each of the board from the broken robot, one at a time, to find out which board is faulty or could this cause the working robot to die aswell?

Could the problem be with the Cabling in the broken robot?

When I eventually get the robot working again I would like to do some mods like Freddie has done so that I am able to put the robot on a charging unit instead of having to spend half an hour taking the rechargeable battery out and replacing them.

Helibot, here is the voltage readout for the CB38P, While on my home made power packs the bottom right reads 4.9 and the bottom left reads 3.8. Now while on the power adapter the right bottom reads 7.6 and the bottom left read 3.8.

@Gerber, before pulling the good robot apart check the media board cables in the picture below, they might appear to make contact under the glue so check each wire individually to make sure it is making contact at the other end. you should have 3.*v on the brown, red, orange and yellow wires. I have had a couple cables with bad connections there that needed resoldering.

Next, there are two power connectors you should check for voltage. In the picture below, the one on the main board that reads 6v with the orange and black cable. the other is close by on the motor board reads 9v has two black and one red. My voltage varies at these points depending onthe power source.

Then, there is a test pad on the bottom of the motor board labled 9v in the picture below it is the last pin top right. make sure there is voltage there.

try this out and let us know if the voltage at these points are near what the lables indicate. Happy tracing!

Hi Freddy,
Thanx for confirming the voltage. 3.8V is good news, it indicates that the part we have identifed is correct. So I think we need to find an alternative part for a "Low dropout voltage regulator with 3.8v output that can supply 300mA of current in a SOT89 package". But I expect its going to be hard to find - so far there were no others that supplied anywhere near 300mA!. Maybe I could look for a different package type (and you may have to solder it off the board with some flying leads.) Anyway I will try to find the right one first!!.
Cheers
Helibot

Gerber,
YOu could swap boards b/n you working and non working robots, but there is a risk that plugging a good board into your bad robot could damage the good board.....so I would'nt try that yet.
If you took both robots apart you could use the good one as a reference to see what the voltage should be at certain points then check the bad robot at these points.

Also another suggestion:- run him off an DC adaptor and use a multimeter to see if he is drawing any current at all when turned on. If he doesnt then it could well be a bad wire or power connection.

Also the eyes and all motors are run by the robot board. If the media board is not plugged in then I think the robots eyes and motors will still all start up. So I think you can assume your problem is with wiring, power supply or robot/motor board. (Ie the media board wont be causing this problem.)

With the greatful help of Jamie we have checked the components on the 3 main boards (i.e. the main robot board, drive board and media board) there doesnÂ’t seem to be any obvious signs of burnt, damaged of lifted, components now. Prieviously I did find AC91 on the media board was lifted which I soldered back on.

@Freddy Â– As you advised above I checked voltages for all the cable you suggested. They all give the correct voltage reading on the multimeter. I also check these cables for continuity and they are fine.

@Hellibot Â– I was thinking of trying each of the boards in turn from the bad robot into the good robot not the other way round, would this possible cause damage to the good robot?

I am already testing the robot with a mains DC adapter and have check it is drawing current with a digital multi meter. It is drawing power up in to the robot when I switch on the power button on the robot.

I disconnected the media board totally as suggested and switched on the robot. Still nothing happens.

Gerber, I agree with Helibot, the problem is not the media board. At this point after ensuring the voltages and contacts, I'd move on to test each board individually on your good bot like you mentioned. At your own risk, try to swap part by part and with a quick finger power on and off the good bot minimizing the risk of something burning up on the good boards. After you identify the bad board(s) we can do the digital magnifier you mentioned to me and I'll look at it, having a second and third pair of eyes look at it never hurts.

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